Connectors, instrument assemblies and methods of connecting or disconnecting electrical connections under power

ABSTRACT

A connector includes a first housing section having a plurality of electrically conductive contacts therein. The connector also includes a second housing section including a plurality of electrically conductive contacts that can form an electrical connection with the contacts of the first housing section. The first housing section and the second housing section are removably connectable and are capable of forming an explosion proof or flame proof housing when connected. The contacts of at least one of the second housing section and the first housing section are movable relative to their respective housing section to align the contacts of the second housing and the contacts of the first housing section during connection of the second housing section to the first housing section. Electrically conductive connection between the contacts of the first housing section and the contacts of the second housing section occurs during connection such that when connection between the contacts of the first housing section and the contacts of the second housing section occurs, the first housing section and the second housing section are in sufficient connection to form an explosion proof housing.

BACKGROUND OF THE INVENTION

[0001] The present invention related to connectors, instrumentassemblies and methods for connecting and/or disconnecting electricalconnections under power. For example, the present invention relatesparticularly to sensor assemblies which can be connected and/ordisconnected under power and to methods of connecting and/ordisconnecting sensor assemblies under power. The connectors, instrumentassemblies and methods of the present invention permit connection and/ordisconnection under power such that the risk of igniting combustible orexplosive gases in the surrounding environment is reduced and preferablyeliminated.

[0002] In a hazardous environment, instruments are designed andinstalled in such a way that any source of ignition the instrumentsmight produce is prevented from igniting combustible gases and/or othercombustible materials in the surrounding atmosphere. For example, thedevice can be placed inside an explosion proof/flame proof enclosure, orthe device circuitry can be made intrinsically safe. Intrinsically safecircuits are generally designed to have limited energy and are unlikelyto produce an ignition source. Explosion proof/flame proof enclosuresare generally designed with enough strength to withstand an internalexplosion while guarding the external atmosphere from the ignitionsource.

[0003] When performing maintenance on an instrument installed in ahazardous environment, a user may desire to disconnect one or moreassemblies or components such as a gas sensor. To perform suchmaintenance under current practice, the user can either declassify thearea by removing all combustible or explosive gases therefrom or byremoving power from the instrument to prevent the possibility of sparkignition creating an explosion or fire. Either of those choices coststhe user significant time and money. Declassification or powerinterruption, however, may not be necessary if the instrument includesintrinsically safe circuitry which limits potential ignition energy.Although use of intrinsically safe circuitry is convenient for the user,the circuitry is more complex, costs more, and may have a power limitthat does not satisfy all desired applications.

[0004] In the mining industry, the Gedcon Model 2400 PermissibleExplosion-proof Connector manufactured by General Energy DevelopmentCorp. of Needham, Mass. purports to provide an explosion-proof connectorfor coupling two sections of multiple wire cable in which disconnectionof the electrical contacts can be made with the explosion proof natureof the connector intact. That connector is also the subject of U.S. Pat.No. 4,198,110. That connector includes a receptacle housing having aninsulative receptacle locked in position therein. A cooperating plug islikewise locked in position in a plug housing. An elongated dagger pin36 in the plug housing cooperates with a receptacle in the receptaclehousing to align male contact pins of the plug with the female contactsockets of the receptacle. A sleeve extends at least partially over bothhousings and threadingly engages with one of the housings to maintainengagement between the plug and receptacle when the sleeve is tightened.Requiring alignment of the elongated dagger pin with the cooperatingreceptacle to mate the contacts within the two housings of the connectorduring connection can be very difficult and substantially reduces theutility of that connector in an instrument assembly and elsewhere. Thus,the connector of U.S. Pat. No. 4,198,110 is generally difficult andcomplicated to connect properly, particularly under conditions typicalof instrument assemblies installed in hazardous environment. Suchinstrument assemblies are often mounted on surfaces in locations whichare not easily accessible.

[0005] It is desirable, therefore, to develop explosion proof connectors(for use, for example, in instrument assemblies installed in hazardousenvironments) and methods of connection and/or disconnection that reduceor eliminate the above-described and other problems with currentconnectors.

SUMMARY OF THE INVENTION

[0006] In one aspect, the present invention provides a connector or ahousing for use in an environment in which a combustible material (forexample, a combustible gas, a combustible dust or a combustible fiber)may be present. The connector includes a first housing section having aplurality of electrically conductive contacts therein. The connectoralso includes a second housing section including a plurality ofelectrically conductive contacts that can form an electrical connectionwith the contacts of the first housing section. The first housingsection and the second housing section are removably connectable. Thefirst housing section and the second housing section are capable offorming an explosion proof or flame proof (referred to collectivelyherein as explosion proof) housing when connected. The contacts of atleast one of the second housing section and the first housing sectionare movable relative to their respective housing section to align thecontacts of the second housing and the contacts of the first housingsection during connection of the second housing section to the firsthousing section. Electrically conductive connection between the contactsof the first housing section and the contacts of the second housingsection occurs during connection of the second housing section to thefirst housing section in a manner such that when connection between thecontacts of the first housing section and the contacts of the secondhousing section occurs, the first housing section and the second housingsection are in sufficient connection to form an explosion proof housing.

[0007] The contacts of the first housing section can, for example, be inelectrical connection with a first cable (for example, a multiple-wireconnector) and the contacts of the second housing section can, forexample, be in electrical connection with a second cable.

[0008] Moreover, the connector of the present invention can also form aninstrument housing wherein one of the first housing section and thesecond housing section includes at least one instrument component inelectrical connection with the contacts of that housing. At least one ofthe contacts of the other of the first housing section and the secondhousing section is adapted to transmit electrical power to theinstrument component when the first housing section and the secondhousing section are connected.

[0009] In another aspect, the present invention provides a method offorming a connection between electrically conductive contacts in anenvironment in which a combustible material may be present, includingthe steps of:

[0010] (a) connecting a second housing section, including a plurality ofelectrically conductive contacts that can form an electrical connectionwith a plurality of electrically conductive contacts of a first housingsection, to the first housing section;

[0011] (b) permitting at least one of the plurality of contacts of thesecond housing section and the plurality of contacts of the firsthousing section to move relative to their respective housing section toalign the contacts of the second housing and the contacts of the firsthousing section during connection of the second housing section to thefirst housing section, and

[0012] (c) making electrically conductive connection between thecontacts of the second housing section and the contacts of the firsthousing section during connection of the second housing section to thefirst housing section in a manner such that when connection between thecontacts of the first housing section and the contacts of second housingsection occurs, the first housing section and the second housing sectionare in sufficient connection to form an explosion proof housing.

[0013] In still a further aspect, the present invention provides a gassensor assembly for use in an environment in which a combustiblematerial may be present including a first housing section having aplurality of electrically conductive contacts therein. At least one ofthe contacts of the first housing section is electrically connectible toa power source. The contacts of the first housing section can, forexample, be seated in a slotted, protective cover to prevent inadvertentcontact with other conductive devices when the first housing section anda second housing section are disconnected.

[0014] The gas sensor assembly also includes a second housing sectionpreferabley having a plurality of electrically conductive contacts thatcan form an electrical connection with the contacts of the first housingsection. At least one of the contacts of the second housing section isin electrical contact with a gas sensor. The first housing section andthe second housing section are removably connectable and are capable offorming an explosion proof housing when connected. The contacts of atleast one of the second housing section and the first housing sectionare movable relative to their respective housing section to align thecontacts of the second housing and the contacts of the first housingsection during connection of the second housing section to the firsthousing section. As described above, electrically conductive connectionbetween the contacts of the first housing section and the contacts ofthe second housing section occurs during connection of the secondhousing section to the first housing section in a manner such that whenconnection between the contacts of the first housing section and thecontacts of second housing section occurs, the first housing section andthe second housing section are in sufficient connection to form anexplosion proof housing.

[0015] Preferably, electrical connection between the contacts of thefirst housing section and the contacts of the second housing section isbroken during disconnection of the second housing section from the firsthousing section in a manner such that when disconnection between thecontacts of the first housing section and the contacts of second housingsection occurs, the first housing section and the second housing sectionremain in sufficient connection to form an explosion proof housing.

[0016] In one embodiment, the second housing section is moved axiallyaway from the first housing section during disconnection and the secondhousing section is moved axially toward the first housing section duringconnection. The second housing section can, for example, includethreading that cooperates with threading on the first housing section sothat rotating the second housing section relative to the first housingsection causes relative axial movement between the second housingsection and the first housing section. In one embodiment, the secondhousing section includes a seating member to which the contacts of thesecond housing are attached. The seating member is rotatably attached tothe second housing member. The seating member includes an abutmentmember that abuts an abutment member of the first housing section toprevent rotation of the seating member of the first housing sectionrelative to the second housing section when the contacts of the secondhousing section are in a predetermined alignment with the contacts ofthe first housing section during connection of the second housingsection to the first housing section.

[0017] The instrument assemblies and methods of the present inventioneliminate the need to declassify an area or the need to interrupt ordisconnect power to an instrument during connection and/or disconnectionof certain housing sections and associated internal electrical contactsthereof by extending the use of an explosion proof enclosure. Becauseelectrical contact of one or more components within the instrument areconnected and/or disconnected while the integrity of the explosion proofenclosure remains intact, any spark thereby created cannot ignite anycombustible gases in the external atmosphere. For example, a sensor orother component can be removed for replacement or repair without risk ofignition. Once the housing sections of the instrument are disconnectedand the sensor or other internal components are removed, the electricalcontact(s) that remain under power are preferably protected from damageor short circuit by a protective, insulating or nonconductive cover, orby being recessed. Replacement of a sensor or other instrument assemblyand reconnection of the housing sections of the instrument areaccomplished in a similar manner.

[0018] Preferably, as the sensor or other internal component is replacedand the housing sections of the instrument are reconnected, contactsassociated with the housing sections are automatically alignedregardless, for example, of the relative rotational alignment of thehousing sections at the beginning of connection, to prevent impropermating or connections. Polarization or unique alignment of one or moreof the contacts can be used for additional assurance that properalignment is achieved. The self-alignment of the contacts of the housingsections during connection thereof facilitates assembly of theconnectors of the present invention. Indeed, such connectors are wellsuited for use in hazardous environments by industrial workers who maybe wearing personal protective equipment.

[0019] In general, as a sensor or other instrument assembly of aninstrument of the present invention is installed, the explosion proofproperties of the enclosure are achieved first, then connection betweenthe electrical contacts is made so that any potential ignition sourcesare contained within the explosion proof enclosure. As a result,intrinsically safe circuitry and any associated power limitations arenot necessary. Moreover, power interruption to the instrument is notrequired, thereby saving the end user time and money while providingmore options than currently are available. The present invention, alongwith the attributes and attendant advantages thereof, will best beappreciated and understood in view of the following detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 illustrates a front perspective view of one embodiment of asensor housing assembly of the present invention in which the first andsecond housing sections are in a disconnected state.

[0021]FIG. 2 illustrates another perspective view of the sensor housingassembly of FIG. 1 in which the first and second housing sections are ina disconnected state.

[0022]FIG. 3 illustrates a perspective view of the sensor housingassembly of FIG. 1 in which the first and second housing sections are ina connected state.

[0023]FIG. 4 illustrates a perspective view of the sensor housingassembly of FIG. 1 in a disassembled or exploded state.

[0024]FIG. 5A illustrates a side view of the sensor housing assembly ofFIG. 1.

[0025]FIG. 5B illustrates a side, cross-sectional and partially cutawayview of the sensor housing assembly of FIG. 1.

[0026]FIG. 6A illustrates a side view of another embodiment of a sensorhousing assembly of the present invention including a labyrinthconnection in which the first housing section and the second housingsection are in a disconnected state.

[0027]FIG. 6B illustrates a side view of the sensor housing assembly ofFIG. 6A in which the first housing section and the second housingsection are in a connected state.

[0028]FIG. 7A illustrates a front view of the first housing section ofthe sensor housing assembly of FIG. 6A and a rear view of the secondhousing section of the sensor assembly of FIG. 6A.

[0029]FIG. 7B illustrates a side, cross-sectional view of a portion ofthe first and second housing sections of the sensor housing assembly ofFIG. 6A in a connected state.

DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention is described, for example, in connectionwith FIGS. 1 through 7B in which gas sensor assemblies are used asrepresentative examples of instrument assemblies of the presentinvention which can be connected and/or disconnected while under powerin an environment in which a combustible material (for example, acombustible gas, dust or fiber) is present without posing an ignitionrisk. One skilled in the art will recognize that instrument assembliesother than gas sensor assemblies can be made connectible and/ordisconnectible under power in the manner described for the gas sensorassemblies of FIGS. 1 through 7B. Similarly, the present invention hasapplicability to the connection and/or disconnection of wires or cablesunder power. As is clear to one skilled in the art, the housings shownin FIGS. 1-3 could just as easily be the mating ends of two wires orcables.

[0031]FIGS. 1 through 5B illustrate one embodiment of a gas sensorassembly 10 of the present invention including a generally cylindricalfirst housing member or section 100 and a generally cylindrical secondhousing member or section 200. First housing section 100 and secondhousing section 200 can, for example, be fabricated from stainlesssteel. First housing section 100 can, for example, be fixed to a wallsection 300 as illustrated in FIG. 1 via a connector such a threadedsection 104 (see, for example, FIG. 2). Wires 106 (see FIG. 5A) can passthrough a passage 109 in connector 104 to connect sensor assembly 10 toa variety of electrical devices such as, for example, a power source,measurement circuitry, a display or a communication system. A sealant ispreferably contained in passage 109 and around wires 106 to assist informing an explosion proof and flame proof housing within sensorassembly 10.

[0032] First housing section 100 and second housing section 200 areconnectible via a threaded section 108 formed around the interior wallof housing section 100 and threaded section 208 formed around theexterior wall of housing section 200. The position of the threading canbe reversed—that is, threading can alternatively be formed on theexterior of housing section 100 and the interior of housing section 200.In that regard, housing sections 100 and 200 are generally aligned to becoaxial and then brought together to make contact between threadedsection 108 and threaded section 208. Housing section 200 can then berotated in a clockwise direction relative to housing section 100 to drawhousing sections 100 and 200 together in an axial direction. Of course,the direction of threading can also be reversed.

[0033] As used herein as a convention in, for example, connection withthe discussion of FIGS. 1 through 5B, the terms “axial” or “axially”refer generally to, for example, an axis A or a similar axis (see, forexample, FIGS. 1 through 3) around which sensor assembly 10 is formed(although not necessarily symmetrically therearound) and to directionscollinear with or parallel to such an axis. The terms “rear” or“rearward” refer generally to an axial or a longitudinal directiontoward threaded connector 104 of sensor assembly 10. The terms “front”or “forward” refers generally to an axial or a longitudinal directionaway from connector 104 and toward metal frit 260 of housing section200. The terms “radial” or “radially” refer to a direction normal toaxis A.

[0034] Sensor assembly 10 and other instruments assemblies of thepresent invention further include at least one set of cooperating ormating electrical contacts (that is, at least one contact on each of,for example, housing sections 100 and 200 that cooperate or mate to forman electrical connection therebetween when housing sections 100 and 200are connected. In general, sensor assemblies such as sensor assembly 10include a plurality of contacts or contact members. Typically, at leastthree sets of contact members (that is, three contact members on eachhousing section) are preferably present in a sensor assembly to providefor a power connection, a ground connection and a data connection.

[0035] For example, sensor assembly 10 preferably includes contacts 110a-e (five in the representative embodiment of FIGS. 1 through 5B)attached to a circuit board 114 of sensor assembly 10. Two of contacts110 a-e are power contacts which may be of a different voltage: onecontact is a ground contact; one contact is a data transmission contact;and one contact is a data reception contact.

[0036] Circuit board 114 and contacts 110 a-e preferably are inelectrical communication with a variety of electrical components suchas, for example, a power source, measurement circuitry, a display (notshown), via wires 106 as described above. Circuit board 114 and contacts110 a-e are preferably seated in a seating or protective member 120(formed, for example, from an insulating polymeric material) wherein aforward surface of circuit board 114 abuts a ledge 122 formed around theinterior of seating member 120. Seating member 120 preferably includes aplurality of slots 124 a-e in a forward surface 125 thereof that alignwith contacts 110 a-e when circuit board 114 is seated within seatingmember 120. Seating member 120 can, for example, include guides 126 thatcooperate with notches 116 formed in circuit board 114 to properly aligncircuit board 114 within seating member 120 so that slots 124 a-e aregenerally aligned with contacts 110 a-e. Seating member 120 preferablyincludes one or more connectors such as flexing tabs 128 that form asecure connection with housing section 100. Tabs 128, for example, forma snap fit with a groove or flange 132 (see FIG. 5B) formed around theinterior wall of housing section 100.

[0037] A potting material (not shown) such as a dielectric polyurethaneresin can be used to, for example, decrease void volume as well as toinsulate, protect (for example, providing chemical resistance) andsecure circuit board 114 within seating member 120. The potting materialcan, for example, be poured into housing section 100 via passage 109after seating member 120 is secured to housing section 100. A seal canbe formed between seating member 120 and housing section 100 via, forexample, an O-ring 130 to prevent the potting resin from passing aroundseating member 120. Once, for example, the polyurethane resin is pouredinto the rear of seating member 120, it can be hardened by drying underheat.

[0038] Housing section 200 includes contacts or contact members 210 a-dthat are attached to a rear side of printed circuit board 214. In theembodiment of FIGS. 1 through 5B, each of contacts 110 a-e is a femaleelectrical contact including two closely adjacent, axially forwardprojecting metal members, and each of contacts 210 a-210 d is a maleelectrical contact including a single axially rearward projecting metalmember that slides between the two metal members of one of correspondingcontacts 110 a-110 d when electrical connection is made therebetween. Ofcourse, the male and female nature of contacts 110 a-e and contacts 210a-d can be reversed as well as intermixed. An electrochemical sensor 216such as the carbon monoxide gas sensor part number 636240 available fromMine Safety Appliances Company of Pittsburgh, Pa. is preferablyremovably attached to the forward side of printed circuit board 214 viapronged contacts 218.

[0039] Printed circuit board 214 is preferably seated in a seatingmember 220 (for example, formed from an insulating polymeric material).Printed circuit board 214 can be properly aligned within seating member220 via the cooperation of guides and notches (not shown) as describedabove. Preferably, a rearward facing surface of printed circuit board214 abuts a flange or ledge 222 (see FIG. 5B) formed around the innerwall of seating member 220. A potting material as described above canalso be used in connection with printed circuit board 214 and seatingmember 220.

[0040] Seating member 220 preferably includes radially outward extendingtabs 224 that seat within a groove 230 (see FIG. 5B) formed in theinterior wall of second housing section 200 so that seating member 220is secured within second housing section 200 to prevent axial movementthereof relative to second housing section 200, but so that seatingmember 220 can rotate about axis A relative to second housing section200. A wave spring 240 and a polymeric disk 242 preferably space sensor216 away from gasket 250 until first housing section 100 and secondhousing section 200 are generally in full connection. In this manner,binding on gasket 250 can be prevented as housing section 200 rotatesabout axis A relative to seating member 200 during connection asdescribed below.

[0041] Preferably, gas enters sensor assembly 10 through a flamearrestor such as metal frit 260 that is positioned on a forward end ofsecond housing section 200. Gasket 250 creates a seal around sensor 216and also assists in preventing potentially damaging gas(es) from thesurrounding environment from coming into contact with the internalcomponents of sensor assembly 10 other than sensor 216. Sensor assembly10 can also include a sealing member such as O-ring 280 which seats in achannel of groove 270 formed in second housing section 200 to assist informing an environmental seal.

[0042] During connection, housing section 200 is first generally alignedto be coaxial with housing section 100 and then brought into connectionwith housing section 100. Housing section 200 is then rotated about axisA relative to housing section 100 which can be fixed, for example, towall 300. Seating member 220 rotates with housing section 200 until aradially inward extending abutment member 228 (see FIG. 4) comes intocontact with a radially outward extending abutment member 132 (seeFIG. 1) of seating member 120. Contact of abutment member 228 withabutment member 132 occurs when contacts 210 a-d are in generalalignment with contacts 110 a-d. Alignment of contacts 210 a-d withcontacts 110 a-d occurs as described above, regardless of the relativerotational alignment of housing sections 100 and 200 about axis A at thebeginning of connection.

[0043] As second housing section 200 is further rotated relative tofirst housing section 100 to bring second housing section 200 intocomplete connection with first housing section 100. Contact of abutmentmember 228 with abutment member 132 maintains seating member 220stationary relative to rotating housing section 200 and maintainscontacts 210 a-d in general alignment with contacts 110 a-d. Additionalassurance that electrical connection will be made only with properalignment can be provided by polarizing one or more of correspondingcontacts 110 a-d and 210 a-d by providing a unique orientation of one ormore such contacts. In the embodiment of FIGS. 1 through 5B, forexample, contacts 110 a-c and contacts 210 a-c are orientated to betangential to a circle of a certain radius about axis A, while contact110 d and contact 210 d are oriented to be in line with a radial lineextending from axis A.

[0044] Further rotation of housing section 200 draws contacts 210 a-dthrough slots 124 a-d and into connection with contacts 110 a-d. Whencontact between contacts 210 a-d and contacts 110 a-d is made,sufficient connection is made between second housing section 200 andfirst housing section 100 such that second housing section 200 and firsthousing section 100 form an explosion proof and/or flame proof enclosuretherebetween. In that regard, an ignition source such as a spark thatcan occur when contacts 210 a-d come into contact with contacts 110 a-dunder power is prevented from igniting gases in the surroundingenvironment. In general, it has been found that an explosion proofenclosure is formed between second housing section 200 and first housingsection 100 when at least approximately six to eight threads or flightsof threading of threaded section 208 are in contact with approximatelysix to eight flights of threading on section 108.

[0045] During disconnection, an explosion proof enclosure remains formedbetween second housing section 200 and first housing section 100 untilcontacts 210 a-d are no longer in contact with contacts 110 a-d. In thatregard, to disconnect second housing section 200 from first housingsection 100, second housing section 200 is rotated in acounter-clockwise direction relative to first housing section 100,thereby causing second housing section 200 to move axially forwardrelative to first housing section 100. After sufficient rotation ofsecond housing section 200, contacts 210 a-d will be drawn sufficientlyforward to disconnect them from contacts 110 a-d. At this point ofdisconnection, a sufficient number of flights of threads 208 of secondhousing section 200 are in connecting contact with threads 108 of firsthousing section 100 that first housing section 100 and second housingsection 200 still form an explosion proof enclosure therebetween. Thus,any spark that might occur during disconnection is prevented fromigniting any combustible gases in the surrounding environment.

[0046] Preferably, a protective covering is formed around each ofcontacts 110 a-e, which still can be under power after disconnectionfrom contacts 210 a-d, to reduce the potential for sparking. In theembodiment of FIGS. 1 through 5B, forward, electrically insulatingsurface 125 of seating member 120 allows access to contacts 10 a-e onlythrough slots 124 a-e thereof to reduce the risk of, for example,inadvertently contacting, damaging and/or short circuiting contacts 110a-e.

[0047] Threading connections afford one convenient manner of forming anexplosion proof enclosure, but are not the only mode of forming anexplosion proof enclosure. For example, FIGS. 6A through 7B illustrate alabyrinth type connection for a sensor assembly 400 including a firsthousing section 500 and a second housing section 600. Second housingsection 600 includes a radially inward projecting key 610 thatcooperates with a doglegged keyway 510 formed in the exterior wall offirst housing section 500. In that regard, key 610 first travels axiallyin keyway 510 as second housing section 600 is moved axially towardfirst housing section 500. Second housing section 600 is then rotated ina clockwise direction about axis A′ relative to first housing section500 to seat key 610 within keyway 510 as illustrated in FIG. 6B.

[0048] First housing section 500 includes one or more spaced, generallycylindrical, axial projections 520 a and 520 b. Likewise, second housingsection 600 includes one or more spaced, generally cylindrical, axialprojections 620 a and 620 b. The outer wall of first housing section 500and projections 520 a and 520 b cooperate with the outer wall of secondhousing section 600 and projections 620 a and 620 b to form a tortuouspath or labyrinth through which an ignition source cannot escape toignite any combustible gases in the surrounding environment.

[0049] As described above, each of first housing section 500 and secondhousing section 600 can be provided with electrical contacts that form aconnection only when first housing section 500 and second housingsection 600 form a sufficient connection to form an explosion proofconnection therebetween. In that regard, the connection between firsthousing section 500 and second housing section 600 must be such that anignition source (for example, an internal flame or an explosionresulting from a spark from connection between electrical contacts)cannot escape into the surrounding environment.

[0050] An explosion proof enclosure can also be formed between only theouter wall of, for example, first housing section 500 and the outer wallof second housing section 600 by having the inner diameter of the wallof second housing section 600 be only very slightly larger than theouter diameter of the wall of first housing section 500 such that anignition source from within the enclosure is unable to ignite anycombustible gases in the surrounding environment when a sufficient axiallength of the wall of second housing section 600 encompasses the wall offirst housing section 500. However, production of housing sections withsuch close or tight tolerances can be difficult and expensive.

[0051] Disconnection and/or connection between contact members of afirst housing section and a second housing section of an instrument canbe made by drawing the contacts together in an axial direction asdescribed for contacts 110 a-d and 210 a-d. However, such matingcontacts need not be brought into contact by axial motion. For example,as is clear to one skilled in the art, the contacts can be brought intoconnection by rotation of one set of contacts into connection withanother set of contacts. As described above, cooperating associated withfirst housing section 500 and second housing section 600 are preferablyautomatically aligned with each other for connection during connectionof first housing section 500 and second housing section 600.

[0052] While the present invention has been generally described inconnection with instruments and instrument assemblies (for example,sensor assemblies), the present invention is also applicable inconnecting and/or disconnecting any electrical connection (including,for example, wires or cables) under power.

[0053] Although the present invention has been described in detail inconnection with the above examples, it is to be understood that suchdetail is solely for that purpose and that variations can be made bythose skilled in the art without departing from the spirit of theinvention except as it may be limited by the following claims.

1. A connector for use in an environment in which a combustible materialmay be present, comprising: a first housing section including aplurality of electrically conductive contacts therein; and a secondhousing section including a plurality of electrically conductivecontacts that can form an electrical connection with the contacts of thefirst housing section, the first housing section and the second housingsection being removably connectable, the first housing section and thesecond housing section being capable of forming an explosion proofhousing when connected, the contacts of at least one of the secondhousing section and the first housing section being movable relative totheir respective housing section to align the contacts of the secondhousing and the contacts of the first housing section during connectionof the second housing section to the first housing section regardless ofthe orientation of the contacts of the first housing section relative tothe contacts of the second housing section prior to connection of thesecond housing section to the first housing section, electricallyconductive connection between the contacts of the first housing sectionand the contacts of the second housing section occurring duringconnection of the second housing section to the first housing section ina manner such that when connection between the contacts of the firsthousing section and the contacts of the second housing section occurs,the first housing section and the second housing section are insufficient connection to form an explosion proof housing.
 2. Theconnector of claim 1 wherein the contacts of the first housing sectionare in electrical connection with a first cable and the contacts of thesecond housing section are in electrical connection with a second cable.3. The connector of claim 1 wherein one of the first housing section andthe second housing section includes at least one instrument component inelectrical connection with the contacts of that housing and at least oneof the contacts of the other of the first housing section and the secondhousing section is adapted to transmit electrical power to theinstrument component when the first housing section and the secondhousing section are connected.
 4. A method of forming a connectionbetween electrically conductive contacts in an environment in which acombustible gas may be present, comprising the steps of: connecting asecond housing section, including a plurality of electrically conductivecontacts that can form an electrical connection with a plurality ofelectrically conductive contacts of a first housing section, to thefirst housing section; permitting at least one of the plurality ofcontacts of the second housing section and the plurality of contacts ofthe first housing section to move relative to their respective housingsection to align the contacts of the second housing and the contacts ofthe first housing section during connection of the second housingsection to the first housing section regardless of the orientation ofthe contacts of the first housing section relative to the contacts ofthe second housing section prior to connection of the second housingsection to the first housing section, and making electrically conductiveconnection between the contacts of the second housing section and thecontacts of the first housing section during connection of the secondhousing section to the first housing section in a manner such that whenconnection between the contacts of the first housing section and thecontacts of second housing section occurs, the first housing section andthe second housing section are in sufficient connection to form anexplosion proof housing.
 5. A gas sensor assembly for use in anenvironment in which a combustible gas may be present, comprising: afirst housing section including a plurality of electrically conductivecontacts therein; at least one of the contacts of the first housingsection being electrical connectible to a power source; and a secondhousing section including a plurality of electrically conductivecontacts that can form an electrical connection with the contacts of thefirst housing section, at least one of the contacts of the secondhousing section being in electrical contact with a gas sensor, the firsthousing section and the second housing section being removablyconnectable, the first housing section and the second housing sectionbeing capable of forming an explosion proof housing when connected, thecontacts of at least one of the second housing section and the firsthousing section being movable relative to their respective housingsection to align the contacts of the second housing and the contacts ofthe first housing section during connection of the second housingsection to the first housing section regardless of the orientation ofthe contacts of the first housing section relative to the contacts ofthe second housing section prior to connection of the second housingsection to the first housing section, electrically conductive connectionbetween the contacts of the first housing section and the contacts ofthe second housing section occurring during connection of the secondhousing section to the first housing section in a manner such that whenconnection between the contacts of the first housing section and thecontacts of second housing section occurs, the first housing section andthe second housing section are in sufficient connection to form anexplosion proof housing.
 6. The gas sensor assembly of claim 5 whereinelectrical connection between the contacts of the first housing sectionand the second housing section is broken during disconnection of thesecond housing section from the first housing section in a manner suchthat when disconnection between the contacts of the first housingsection and the contacts of second housing section occurs, the firsthousing section and the second housing section remain in sufficientconnection to form an explosion proof housing.
 7. The gas sensorassembly of claim 6 wherein the second housing section is moved axiallyaway from the first housing section during disconnection and the secondhousing section is moved axially toward the first housing section duringconnection.
 8. The gas sensor assembly of claim 7 wherein the secondhousing section includes threading that cooperates with threading on thefirst housing section so that rotating the second housing sectionrelative to the first housing section causes relative axial movementbetween the second housing section and the first housing section.
 9. Thegas sensor of claim 8 wherein the second housing section includes aseating member to which the contacts of the second housing are attached,the seating member being rotatably attached to the second housingmember, the seating member including an abutment member that abuts anabutment member of the first housing section to prevent rotation of theseating member of the second housing section relative to the secondhousing section when the contacts of the second housing section are in apredetermined alignment with the contacts of the first housing sectionduring connection of the second housing section to the first housingsection.
 10. The gas sensor of claim 9 wherein the contacts of the firsthousing section are seated in a slotted, protective cover.
 11. Theconnector of claim 1 wherein the contacts of the first housing sectionare recessed in a nonconductive cover.
 12. The gas sensor assembly ofclaim 5 wherein the plurality of electrically-conductive contactscomprises a power connection, a ground connection and a data connection.13. The gas sensor assembly of claim 5 wherein theelectrically-conductive contacts of the first housing are receptaclesand the electrically-conductive contacts of the second housing are pins.14. The connector of claim 1 wherein electrical connection between thecontacts of the first housing section and the second housing section isbroken during disconnection of the second housing section from the firsthousing section in a manner such that when disconnection between thecontacts of the first housing section and the contacts of second housingsection occurs, the first housing section and the second housing sectionremain in sufficient connection to form an explosion-proof housing. 15.The connector of claim 14 wherein the second housing section is movedaxially away from the first housing section during disconnection and thesecond housing section is moved axially toward the first housing sectionduring connection.
 16. The connector of claim 15 wherein the secondhousing section includes threading that cooperates with threading on thefirst housing section so that rotating the second housing sectionrelative to the first housing section causes
 17. The connector of claim16 wherein the contacts of the first housing section are recessed in anonconductive cover.
 18. The connector of claim 1 wherein the pluralityof electrically-conductive contacts comprises a power connection, aground connection and a data connection.
 19. The connector of claim 1wherein the electrically-conductive contacts of the first housing arereceptacles and the electrically-conductive contacts of the secondhousing are pins.
 20. The method of claim 4 further comprising the stepof breaking the electrical connection between the contacts of the firsthousing section and the contacts of the second housing section such thatwhen disconnection between the contacts occurs, the first housingsection and the second housing section remain in sufficient connectionto form an explosion-proof housing.